Method for continuously straightening sheet material



Jan. 24, 1961; E. M. ALLEN 2,968,856:

METHOD FOR CONTINUOUSLY STRAIGHTENING SHEET MATERIAL Filed March 8, 19572 Sheets-Sheet 1 l (9 I I w u- I 00 I INVENTOR. EUGENE M. ALLEN ATTORNEYJan. 24, 196E E. M. ALLEN 2,968,

METHOD FOR CONTINUOUSLY STRAIGHTENING SHEETMATERIAL Filed March a, 19572 sheeis-srieet 2 FIG. 3

FIG. 4

INVENTOR.

EUGENE M. ALLEN BY ATTORNEY United States Patent METHOD FGR CONTINUOUSLYSTRAIGHTENING SHEET MATERIAL Eugene M. Allen, Elizabeth, N.J., assignorto American Cyauamid (Zompauy, New York, N.Y., a corporation of MaineFiled Mar. 8, 1957, Ser. No. 644,886

3 Claims. (Cl. 26-515) This invention relates to an improved automaticweft straightener and method.

The problem of apparatus for straightening the weft of woven fabrics inorder to insure that the weft yarns be disposed in right angularrelation to the warp yarns and to insure that they shall be straightfrom one selvedge to the other of the fabric has been a serious one. Twotypes of weft yarn misalignment are present. In the one case the weftyarns, While parallel to each other in straight lines, are not at rightangles to the warp yarns. The second case is that the Weft yarns, whilegenerally at right angles to the warp yarns, are not parallel but arebowed in one or the other direction. Of course, both types ofmisalignment may occur at the same time; that is to say, where the weftyarns are not at right angles to the selvedges and are also not parallelto each other but curved.

The problem for certain classes of fabrics has been solved completelyand satisfactorily by the device and method described and claimed in thePatent No. 2,638,656, May 29, 1953, to Tuttle, Maclsaac and Sturtevant.It is with an improvement to the method and apparatus of the said patentthat the present invention deals. Essentially, thepatent provides forweaving a narrow band of weft threads at periodic intervals which aretreated with a fluorescent or phosphorescent pigment. As the fabricpasses through the machine, it passes under a row of ultraviolet lightswhich illuminate a. band across the fabric and at right angles to theselvedges. A series of photocells or other photoelectric devices aredisposed so that they receive visible, but not ultraviolet, light fromthe illuminated band of fabric. When the band of weft threads treatedwith the colorless fluorescent or phosphorescent material is illuminatedby the ultraviolet lights, it fiuoresces; and the fluorescent light,which is in the visible spectrum, is received by the photocells. If theweft threads are at right angles to the selvedges and are parallel, allphotocells receive visible light at the same time and there is nodifferential signal in the amplifier circuits fed by the electricalsignals from the photocells. If the weft threads are parallel to eachother but are not at right angles to the selvedges, the band iseffectively a diagonal and it comes into the illumination of theultraviolet lights at different times, one edge being illuminated beforethe other. This produces a differential signal between the outerphotocells and, after amplification, this controls motors which vary therate at which the fabric edges are pulled, the variation,

of course, being in the direction to restore parallelism of the weftthreads and a right angled orientation with respect to the selvedges. Inthe case of a curved or bowed band, either the central photocells arefirst illuminated or the outside ones are first illuminated. In 132,968,856 Patented Jan. 24, 1961 2 either event, a differential is setup between the signals from the outside photocells and from the centralphotocells which again, after amplification, controls a motor whichrotates certain bowed rollers which have the effect of straightening outthe weft threads by pulling the central portion of the fabric eitherfaster or slower than the edges, as the case may be. If both types ofdistortion of the weft threads occur at the same time, then there willbe a differential signal of both types and both correcting motors willbe actuated in the proper direction.

Despite the complete and elegant solution of the weft straighteningproblem with most fabrics which is effected by the method and apparatusof the above-referred-to patent, problems have arisen recently, andthere is a growing demand for fabrics which cannot be straightened bythe patented method. The problem is posed by the desirability forcertain uses of dyeing the whole fabric with colorless fluorescent dyesor brighteuers and is even a problem in the case of dyed material whereone or other of the dyes, though colored, is also fluorescent. Wheneverthere is material normally in the fabric, either colored or colorless,which iluoresces, the method of the above-referred-to Tuttle et a1.patent cannot be used; yet with such fabrics, the problem of weftstraightening is just as serious as with ordinary fabrics which are notdyed with fluorescent materials. It is with the solution of this problemthat the present invention deals, and it is a further advantage of thepresent invention that it is equally applicable to fabrics, whether ornot they have an overall dyeing of fluorescent material.

The present invention does not use a narrow dyed band of fluorescentmaterial, but, on the contrary, uses phosphorescent material anddisplaces the band illuminated by the ultraviolet light and the bandseen by the photocells a few inches so that no fluorescent light strikesthe photocells. An extremely sharp separation is perfectly achievedbecause the fluorescent substances which are normally applied to fabricshave an extraordinarily rapid decay of emitted fluorescent light afterthe ultraviolet illumination ceases. With almost all fluorescentmaterial half lives are obtained which are of the order of microsecondsor less. Phosphorescence, however, does not decay at anywhere near sorapid a rate and there are many phosphors which have relatively longhalf lives. However, it is not necessary that a phosphor phosphorcscefor many seconds. It is sufficient if there is substantialphosphorescent light emitted after a second or two or even a majorfraction of a second. The fabric passes through the straighteningmachine quite rapidly at a rate of a good many inches a second. Thus,even with phosphorescent material of fairly short half life, there isstill adequate phosphorescent light emitted when the band of ultravioletillumination and the band of fabric seen by the photocells is displacedby three or four inches so that no critical control is involved.

When the present invention is used in which the Weft straightening iscontrolled not by any light which is reemitted at the time ofultraviolet irradiation but by phosphorescent light which is continuedfor a considerable period after illumination has ceased, the machine canbe used interchangeably with fabrics which have no fluorescent overalldyeing or pattern and those which have been dyed with a brightener orother fluorescent material. No change of adjustment in the machine is rneeded and, therefore, the method and apparatus is of atively there arevery few of them which can be practically applied to fabrics, theintensity of phosphorescence is not as high as the intensity offluorescence. As a result it is desirable to use somewhat more sensitivephotoelectric radiation detectors, for example photomultiplier tubeswhich may however be operated at very moderate voltages with greaterreliability than for extremely high voltage power supplies. About theonly other requirement of the present invention which is not met in theoriginal Tuttle method and apparatus and which is critically dimensionedis that the field of view of the photocells must be rather sharplyadjusted and so care must be taken that their orientation is maintainedthroughout the operation of the machine.

Among the phosphorescent chemicals which can be practically dyed on theweft threads are the following.

2,2'--phenylene-bis- [(6)-chlorobenzimidazole] 2-(3-dibenzofuryl)-2-naphtho( 1,2)triazole-6-sulfonic acid sodium salt2-(3-dibenzothienyl)-2-naphtho[1,2]triazole 6 sulfonic acid H O 3S-W%N K\S Sodium-2-( 2-methoxy-3 -dibenzofuryl -naphth0( 1,2)-triazole-6-sulfonate onto NaOaS /N Sodium 2-(2-dibenzothienyl) 2naphtho(1,2) triazole-G- sulfonate Na0n%N\N 2- (p- [Z-benzimidazolyl]phenyl) -2-naphthol( 1,2) triazole- 6-sulfonic acid sodium salt SOaNa2,2'-(4,4'- [3,3'-dichlorodiphenylene] )bis-2-naphtho( 1,2)

triazole-6-sulfonic acid disodium salt [NaOaS 5 -amino-2-phenyl-2-pyrido[2, 3-d] -v-triazole 5 (6) -acetamido-x-acetyl-2,2'-dibenzimidazoleNHOOCH -CO N N H H 5'(6')-acetamido-2,2'-dibenzimidazole 1 ethanolacetic ester While the invention is in no sense limited to thephosphorescent materials enumerated above, these constitute thepreferred materials. It is possible to apply inorganic phosphors but ingeneral their application to Weft threads is more difficult than withthe b-righteners which have chemical affinity for the weft yarns.However, with certain synthetic materials in which the phosphorescentmaterial has to be applied with the aid of film-forming material, othertypes of phosphors such as inorganic phosphors are equally suitable.

The invention will be described in greater detail in conjunction withthe drawings in which:

Fig. l is a perspective of a weft straightening machine;

Fig. 2 is a plan view of a portion of the fabric with weft threads notat right angles to the selvedges;

Fig. 3 is a similar plan view with weft threads bowed; and,

Fig. 4 is a similar plan view in which the weft threads are both bowedand not at right angles to the selvedges.

Fig. 1 is substantially the same as the first figure of the Tuttlepatent referred to above except for the orientation of ultravioletilluminants and photoelectric detectors. Also the electrical circuits ofthe amplifiers are shown purely as a block diagram since the samecircuits used in the Tuttle patent are equally applicable here. A lengthof fabric 1 having spaced bands 2 of weft threads dyed with thephosphorescent compound Q HR N N passes between a pair of rolls 3 and 4under an idler roll 5 to a canting roll 6 and then down under a secondidler roll 7. The hand then passes over an idler roll 8 and then betweena pair of how straightening rolls 9, 9, under another idler roll 10 andfinally under a row of ultraviolet lights 11 which illuminate a narrowband across the moving material some three or four inches from the bandseen by the three photocells 12, 13 and 14, finally passing to a tenterhaving endless chains 15 and 16 driven by the pulleys 17 and 18.

The canting roll 6 is journalled for rotation in suitable bearing blocks19 and 20 which are connected to a screw shaft 21 through links 22 and23. The screw 21 is driven by the motor 24 through gears 25 and 26. Ifthe web of fabric is skewed, the skew can be corrected by rotation ofthe motor 24 in the proper direction which elevates one end of thecanting roll 6 and lowers the opposite end.

The skew corrector cannot correct a bowing of the band and this iseffected by the bowing correcting rolls 9, 9 which are journalled inblocks 27 and 28, the shafts of the two rolls being respectively driventhrough bevelled gearing 29 and 39 by the reversible bow correctingmotor 31. The rotation of the bowed correcting rolls 9 and 9 can correctany bowing which is present in the web passing under and over. Theoperation of bow correcting rolls is conventional in the art and isdescribed in U.S. Patent 2,492,737 of December 27, 1949.

The outside photoelectric detectors 12 and 14 are connected into thedifferential signal input bridge 32 of the amplifier 33 which drives themotor 24 on response to a differential signal. Similarly there is aconnection from the outer photoelectric detectors 12 and 14 and thecenter photoelectric detector 13 to a differential bridge input 34 whichfeeds an amplifier 35 which drives the motor 31. As has been pointed outabove, the differential signal inputs 32 and 34 are of conventionaldesign as shown in the Tuttle patent and so are the amplifiers. Theirdesign is not affected by the present invention except insofar, ofcourse, that the electrical components of the differential inputs mustmatch the photoelectric detectors used. Thus, for example, aphotomultiplier tube generates a signal of considerably higher impedancethan does an ordinary photocell of the barrier-layer type and theelectrical circuit in the differential input must of course havesuitable impedance and other characteristics to match the signal whichit receives.

In Fig. 1 the web of fabric is shown with bands 2 parallel and at rightangles to the selvedges. In other words, it shows a web with straightwefts. When the band 2 passes through the zone of illumination of theultraviolet lamps 11 and then passes under the band scanned by thephotoelectric detectors 12, 13 and 14, all three photoelectric detectorsare actuated at the same time. There will therefore be no differentialsignal either in the input 32 or the input 34 and, hence, neither motor24 nor 31 will rotate, which is of course as it should be since thephotoelectric detectors show that the web is straight as far as the weftthreads are concerned. If, however, a web with the bands 2 shown in Fig.2 passes through the machine, photoelectric detector 14 will receivephosphorescent light before detector 12. There will however be nodifference between the combined detectors and detector 13. Therefore, adifferential signal will be generated in 32 which causes the motor 24 toturn in a direction to correct the skew present. The length of timeduring which the motor 24 turns is, of course, proportional to theamount of skew because the turn will not stop until photoelectricdetector 12 is illuminated. The correction for skew will cause the nextilluminated band 2 to be straight and so there will be no further signalin 32 and no rotation of the motor 24 until the web again becomesskewed.

If the web is bowed, as shown in Fig. 3, the outer detectors 12 and 14will be illuminated at a time when there is no illumination on thecentral detector 13. This will cause no differential signal in 32. butwill cause a differential signal in 34. As a result this is amplified in35 and the motor 31 turns in a direction to eliminate the bowing.

If the web is both bowed and skewed, as is shown in Fig. 4, then whenthe band 2 passes under the photocells there will be produced adifferential signal both in 32 by reason of the skew and in 34 by reasonof the bow, and so both motors 24 and 31 will turn in the properdirection to straighten out the web again.

The bands shown in the web described above are of phosphorescentmaterial. If the remainder of the web is coated with fluorescentmaterial, it will be apparent that this will in no way affect theoperation of the machine because the portion of the web illuminated bythe ultraviolet light is removed from the portion seen by thephotoelectric detectors by a distance corresponding to a second or twoin time. The particular phosphorescent compound described has asubstantial fraction of a second. This is so enormously long compared tothe fraction of a microsecond, which is the half-life of the ordinaryfluorescent material, that the photoelectric detectors are respondingonly to phosphorescent radiation and they are not affected by thefluorescent light from the web as a whole, for this has completely diedout before it is brought within the field of view of the photoelectricdetectors.

It has been pointed out above that the exact method of applying thephosphorescent material to the bands of weft threads is not important solong as the band is of suitable width. When dealing with the compounddescribed, Which is substantive for cellulosic fabrics, if the web is acellulosic fabric the outside of the weft bobbin can be very quicklydyed with the phosphorescent compound so that penetration is only slightand only the outer layer of the bobbin is dyed. When the loom isoperated which weaves the web, this short length of dyed weft yarn willproduce a relatively narrow band. Where phosphorescent materials areused which are not substantive to the fabric of the web, it becomesnecessary to apply them in the form of a band by other means, such asprinting and the like. The present invention is of course not concernedwith the particular suitable and conventional means of applying thephosphorescent material to the weft threads.

I claim:

1. In a method of controlling electrically-operable mechanical means formaintaining the contour of a moving length of web material wherein aplurality of photoelectric detectors are associated with saidelectricallyoperable mechanical means and are adapted to view only atransverse band of said Web, the differential output of differentphotoelectric detectors controlling said elec trically-operablemechanical means; the improved method permitting operation when said webcarries fluorescent material, said improvement comprising: applyingphosphorescent material, other than any luminescent material normallycarried by said web, in spaced transverse stripes on said web;illuminating with ultraviolet light substantially only a transverse zoneacross said web; placing said photoelectric detectors to receive lightemitted from any one transverse band containing said phosphorescentmaterial only after said web has been moved through and a predetermineddistance beyond said illuminated zone, said predetermined distance beingsufiicient so that the detectors receive a substantial portion ofphosphorescent light emitted from said one transverse stripe which hasbeen but no longer is being illuminated by said ultraviolet light,whereby said photoelectric detectors receive substantially nofluorescent light emitted by said transverse stripe.

2. A method according to claim 1 in which the phos- 2,968,856 7phorescent material is substantive to weft threads of a woven web andperiodic lengths of weft thread are dyed with said phosphorescentmaterial before weaving.

References Cited in the file of this patent UNITED STATES PATENTS Amethod r ing o claim 2 in which the phose '1'5- '-2-h phorescent matena1s ammo p enyl 2 pyndo [2,3 d] 5 2,808,407 Ackermann et a1. urn-Oct- 11957 v-triazole having the formula:

OTHER REFERENCES Handbook of Chemistry and Physics, 35th edition,

1953-1954, by Chemical Rubber Publishing Co., 2310 zN Q 10 SuperiorAvenue, NE, Cleveland, Ohio, page 2717.

N N (Copy 1n DlVlSlOIl 21.)

